Expansion engine



J; M. CLARK EXPANSION ENGINE March 16, 193'17.

Filed Aug. 2l, 1955 2 Sheets-Sheet l March 16, 1937. g, M CLARK2,074,165

EXPANS ION ENGINE Filed Aug.'211955 2 sheets-sheet l2 /f u INVENTOR. JamMem# am.

l WLM' ATTORNEYS.

Patented Mar. 16, 1937 UNITED? sTA'rEs i .2nuits OFFICE 14 Claims.

This invention relatesto expansion engines, especially to engineshavingv a fluid-pressure cylinder with a piston Working therein, andadmission and exhaust ports controlled by a main valve, and moreparticularly to such Vengines which are characterized by an auxiliaryexhaust passage controlled by an auxiliary exhaust valve.

A primary object of the present invention is to provide, to an extentheretofore unrealized, for relieving back pressure in the cylinder bypermitting a complete free exhaust therefrom independently of thatpermitted by the main valve; also, in pursuance of this primary object,another object is to provide for connecting the auxiliary l valve toappropriate Working parts of the engine,

and preferably to the main reverse-shaft-link, in

such a manner that full motion will be imparted thereby to effect freeexhaust to an optimum extent.

Another object is to provide means by which the operation of theauxiliary free exhaust valve gear will be under direct manual control ofthe engineer, by .governing means independent of the usual means forcontrolling the main valve,

but conveniently disposed in relation thereto for manual operation, asin the cab of a locomotive.

Another object of the invention is to provide for throwing the auxiliaryvalve gear entirely out of `operation at the will of the engineerwithout in any Way aiecting normal operation of the main Valve gear.

Still another object is to provide for effecting the last-named objectby means of a device acting in aid of the auxiliary exhaust valve, butpermitting the latter to idle without functioning, at

times when free exhaust is not desired; also to utilize for this purposea piston-'type valve as the auxiliary valve, and a` sleeve memberdisposed telescopically upon this piston valve, with a levercontrolling-system running to the cab by which the sleeve may be setreadily at any time to cut 01T the exhaust entirely, or to set it at anydegree of cut-off without affecting the coordinative relation betweenthe valves.

Other objects and advantages will appear as the description of theparticular physical embodiment selected to illustrate the inventionprogresses, and the novel `features will be particularly pointed out inthe appended claims.

In describing the invention in detail, and the particular physical.embodiment selected to illustrate the invention, reference Will be hadto the accompanying drawings and the several views 5,-; thereof, inwhich like characters of reference designate like parts throughout theseveral views, and in which:

Fig. 1 is an elevation of the invention, partly in section through thedriving cylinder-and the main and auxiliary valve casings;

Fig. 2 is a fragmentary,`detail view of a part of the mechanism shown inFig. l, illustrating certain of the parts in a different operativeposition;

Fig. 3 is a vertical section taken on the line 3-3 of Fig. 1;

Fig. 4 isa fragmentary, detail View similar to Fig. 2, showing amodication;

Fig. 5 is a similar view illustrating another modication.

In the now-preferred embodiment of the invention selected forillustrative disclosure thereof, the part designated by the referencecharacter II is the duid-pressure cylinder of an expansion engine upon asteam-propelled locomotive, and I 2 designates the piston workingtherein, I3 being the piston-rod, I4 the cross-head, I5 the maindriving-rod, running to crank-pin I6 of driving Wheel Il; I8 is theeccentric-rod, running to arm I9 on the main reverse-link 22; 20 is thereverse shaft, 2l the reverse-shaft-arm, 23 the lifting-link and 24 thereverse-shaft-lever; these forming parts of connections running to thecab of the engine (not shown), to permit manual control thereof by theengineer.

The valve gearY and associated parts designated as above may be ingeneral of the conventional form illustrated, or of other suitableconstruction, as are also the main valve 25, shown as a piston valveoperating in a steam chest Z6 having a suitable main admission passage2l', and main admission and exhaust ports 28 and 29: main exhaustpassages are shown at 3l and 32', and 30 designates suitable orifices inthe valve-seatliners 33, the ports designated as above being all adaptedto be controlled by the main valve 25, which is in turn actuated andcontrolled by suitable connections Wth the main link 22, suchconnections preferably including a radius-rod 34, anda combination-leverof conventional form as 35, 36, associated with the cross-head I4, bywhich it may desirably be actuated in the manner characteristic of theso-called Walschaert valve gear, or of any other analogous or suitablevalve gear, the particular form shown being merelyillustrative and notlimitative.

In an extension of the valve chest, as 31, is

shown an auxiliary valve 38, taking the form, in

the instance' illustrated, of a` piston valve, al-

though by such illustrative disclosure it is not intended to exclude theuse of other suitable forms of valves; this auxiliary valve beingadapted to control auxiliary passages 39 and 40, either 5 of which isadapted, selectively, to permit full and free exhaust from the maincylinder when so desired, independently of the exhaust controlled by themain valve 25.

As a convenient and suitable means to operate l this auxiliary valve 38,its stern 4| is connected to the main link 22, as by a pivot 42 fromwhich a rod 43, or system of rods and levers designated generally by thereference character R, runs to a pivot 45 on main link 22, and in thepreferred l form of the invention illustrated in Figs. 1, 2 and 3, Ihave shown a secondary link 44 mounted swingingly about a pivot post 46carried by the frame F, the secondary link 44 constituting an adjustableelement or instrumentality in connection with a pivot block 4 upon whichis carried lever 43 by a stud 43a said block being movable slidingly inthe body slot 3 of link 44. The

end 48 of lever 43 is connected pivotally, as by a lifting link 49,(which may be termed the secondary lifting link, as it is identical inform with the main lifting link 23) With the bell-crank lever 50, whichforms part of a system of levers designated generally A, running to theengine cab (not shown), to permit manual control by the engineer of theauxiliary valve independently of the usual control of the main valvethrough main link 22, as already described.

The various operations of this secondary link will be described more atlength hereinafter, but it should be noted that when it is adjusted tothe mid-position shown in Fig. 2, or rather when the pivot block 4 isadjusted so as to bring the pivot stud 43a into axial registration withthe pivot point 45 of the secondary link, as in Fig. 2, the auxiliaryvalve 38 will be put thereby entirely out of operation, and the mainvalve will` then be relied upon to take over the entire government ofexhaust operations, in normal fashion, and completely withoutinterference. 45 So far as I am aware, this provision for effecting afull stroke of such an auxiliary valve to permit complete free exhaustunder selective control by the engineer at all times, has never beenmade before, and I regard this notable improvement in the art asconstituting the underlying idea of means to which my claims aredirected generically except so far as otherwise limited to particularphysical embodiments of the said idea of means. 55 It will be readilyunderstood from the foregoing disclosure that when the parts are in therelative positions illustrated in Fig. 1, steam will be admitted to thefront end I9 of cylinder following the course indicated by the arrows inFig. 1, the main steam supply entering the chest 26 from S through port2'1, and leaving the chest through the orifices 30 in bushing or liner33, which are at all times in communication with ports 28, through whichthe live steam has ac- 65 cess to the front end of the cylinder.

The main valve at this event is disposed with its front piston m' inposition to block exhaust to the main exhaust passage 32, and theauxiliary valve 38 is so disposed as to block the auxiliary exhaustpassage 49 by means of the auxiliary valve piston a; while at the otherends of the main valve and of the auxiliary valves respectively, thevalve piston m of the main valve and the valve piston a of the auxiliaryvalve are so disposed as to leave the main exhaust passage 3| and theauxiliary exhaust passage 39 wide open for spent steam passing throughpassage 29 and orifices 30 in the liner 3 also having access to the mainexhaust passage through an orice 5| provided between the auxiliary andmain exhaust passages. It is to be understood that the auxiliarypassages 39 and 49 respectively surround the liners or bushings 33, sothat when either of the valve pistons a or a, as the case may be,occupies its innermost position, as that occupied in Fig. 1 by thepiston valve a, for example, the steam proceeding from port 29 will begiven free and full opportunity to exhaust, regardless of whether thevalve piston m of the main valve occupies the position illustrated inFig. 1, or whether the main valve 25 has been retracted to a position inwhich said piston valve m" covers the orices 30 in Whole or in part.

It is also true that when one of the piston valves of the auxiliaryvalve occupies its outermost position, as in the case illustrated inFig. 1 with respect to the valve piston a', the auxiliary exhaustpassage controlled thereby will be closed, as is the passage 40 inFig. 1. In the instance illustrated the main exhaust passage 32 iscompletely closed, also, but it will be understood that the auxiliaryvalve may be disposed to close the auxiliary exhaust passage completelyeven when the main exhaust passage is desirably open in whole or inpart, as during the event of starting the engine, or at such times theauxiliary exhaust may also be opened in Whole or in part, its regulationbeing entirely under the manual governance of the engineer, by means ofthe lever system A, independently of the regulation of the main valve,as already disclosed.

Accordingly the main valve can be linked up or cut olf to any point forhigh speed work, independently of the free exhaust valves, and my novelarrangements for operating the auxiliary valves will give a free exhaustWhile the main valve is traveling a short stroke on cut off, and thus myinvention accomplishes the primary object stated in the openingparagraphs of this specication, viz., to provide, to an extentheretofore unrealized, for relieving back pressure in the cylinder whilepermitting a complete free exhaust therefrom independently of thatpermitted by the main valve. I have found on test that with a 50%cut-off on the main valve and the auxiliary valves wide open forcomplete free exhaust, I am able to effect a gain of at least 20% inpower, and the gain is in proportion to the size of the engine.

The particular physical embodiment of the invention shown in Fig. l ismerely illustrative, as already mentioned, and as an indication ofpossible changes or modifications of structure to meet the requirementsof particular installations, or to eiect economies of space, I haveshown in Fig. 4 an arrangement of parts in which the variousinstrumentalities that bear reference characters corresponding to thoseof Fig. 1, may be regarded as similarly formed and co-operating in thesame fashion; but it will be noted that the secondary link 44A shown inFig. 4 is provided with a relatively long arm or extension 54, and thatthe rod running from this part to the main link 22 is connectedpivotally to the latter at the same pivotal point 58 to which isconnected the eccentric rod i8.

It will also be noted that the pivot point of the secondary link support51 is disposed at the upper end of said link and a somewhat longeradjustive range of movement has been provided for, all at one side ofthe pivot point 51.

lnanother modification of the invention, as

shown in Fig. 5, I have provided in a suitable extension 60 of the valvecasing a cylindrical seat 6l, 62, having main exhaust passagesv and.ports 63, 64, and auxiliary exhaust passages and ports 65, 66.

The auxiliary valve 68 in this device is of the pistonv typeV and haspiston valves p' and p" so disposed that` when the engine is to bebacked up these valves will close the main exhaust ports, asillustrated.

In this structure, the valve`istem61 is connected to the main link 22 bymechanismincluding link 69, lever 1B and link 1| operating in well-knownreversal of the direction of motion derived from main link 22, and theauxiliary piston valves continue to reciprocate aslong as the main link22 operates. The sleeve 12 as shown in this figure is provided with asystem of levers designated generally by the reference `character L,which may desirably be extended to the engine cab, (not shown) so thatthe sleeve may be shifted independently of the operation of theV mainvalve b-y the means hereinbefore described with respect to otherembodiments of the invention.

By operation of the lever system L manually, the sleeve 12 may be set atany desired position within its range of movement; viz, from one extremeposition in which all o-f the parts are cut oil?,- so that the auxiliaryvalve mechanism idles (i. e., is ineiective, though moving), to aposition in which, asshovvn in Fig. 5, al1 of the parts 13, 14, 15 and16 are open, affording complete free exhaust. By setting the sleeve 12suitably to a selected intermediate position the parts may be cut Oitothe extent desired, in which latter instance ports 16, 13, 14 andV 15,in the extension will be brought suitably Vinto registry` withappropriate portions of the ports 63, 64, 65 and 66.

I have described what I believe to be the best embodiments of myinvention. I do not Wish, however, to be conned to the embodiment shown,but what I desire to cover by Letters Patent is set forth in theappended claims.

I claim:

1. A valve gear for an expansion engine of the type characterized by afluid-pressure cylinder with a reciprocating piston working therein andhaving main admission and exhaust ports and a main valve adapted tocontrol said ports for general admission and exhaust purposes; saidvalve gear being further characterized by an auxiliary exhaust passageand an auxiliary exhaust valve exclusively for controlling exhaustthrough said last-named passage, and means to permit selective manualcontrol of said valves at all times, whereby complete free exhaust fromsaid cylinder is provided.

2. A valve gear for anexpansion engine of the type characterized by afluid-pressure cylinder with a reciprocating piston Working therein andhaving an admission port, a main exhaust passage, a main exhaust port, amain valve adapted to control both of said ports for general exhaustpurposes, and means for actuating and controlling said main valve; saidvalve gear being further characterized by an auxiliary exhaust passageand an auxiliary exhaust valve for controlling said last-named passage,whereby free exhaust from said cylinder may be permitted independentlyof control by the main valve; and means to control said auxiliary valveindependently of the main valve.

3. A valve gear for an expansion engine of the type characterized by afluid-pressure cylinder witha reciprocating piston Working therein, andhavingV an admission port, a main exhaust passage, a main valve adaptedto control said port and Apassage for general exhaust purposes, andmeans for actuating and controlling said main valve, including aconveniently disposed manual governing device for said main valve; saidvalve gear being further characterized by an auxiliary valve and anauxiliary passage controlled thereby, whereby free exhaust from saidcylinder may be permitted independently of the main exhaust, and alsocharacterized by manually operable governingvmeans `for said auxiliaryvalve disposed conveniently vnear to said first-named governing devicebutoperable independently thereof.

4. A valve gear for an expansion engine of the type characterized by afluid-pressure cylinder with a reciprocating piston Working therein andhaving an admission port, a main exhaust passage, a main valve adaptedto control said port and passage for general exhaust purposes, and meansfor actuating and governing said main valve, including a main reverselink combined and co-operating with appropriate working parts of theengine; said valve gear being further characterized by an auxiliary`valve and an auxiliary exhaust passage controlled thereby, saidauxiliary valve being -provided with connections to said main link,whereby free exhaust from said cylinder may be permitted independentlyof the main exhaust, and means to control the operation of saidauxiliary valve manually, independently of said main valve. l

5. A valve gear for a steam engine orlike expansion engine of the typecharacterized by a fluid-pressure cylinder and a piston working thereinand having an admission port, a main exhaust passage, a main valveadapted to control said admission and exhaust generally, and means foractuating and governing said main valve including a main reverse link,combined and cooperating with appropriate working parts of the engine,said governing means including a device conveniently disposed for manualgovernment of said main valve; said valve gear being furthercharacterized by an auxiliary valve and an auxiliary exhaustpassagecontrolled thereby, whereby free exhaust from said cylinder may bepermitted independently of the main exhaust, said auxiliary valve havingdirect, adjustable, connections with said main link, and manualgoverning means to adjust said connections for said auxiliary valve,said last-named governing means being arranged in convenient dispositionfor operation independently of said first-named governing device.

6. A valve gear characterized by the elements combined and co-operatingas set forth in claim 1, said valve gear being further characterized byhaving said auxiliary valve formed as a reciprocating piston and byhaving a sleeve surrounding said piston valve slidingly as an instru--mentality of said auxiliary-valve-control means; andmeans operablemanually to move said sleeve to cut off said free exhaust at will,irrespective of Whether or not said main exhaust is open,

7. A valve gear of the class described, comprising a main valve adaptedto control the main admission and exhaust normally; an auxiliary valveadapted to control an auxiliary passage for free exhaust, being arrangedfor normal operation in supplement of the main exhaust, and means to cutoff said auxiliary exhaust passage at will, while said auxiliary valvecontinues to move.

8. A valve gear forA expansion engines of the type characterized by afluid-pressure cylinder with a reciprocating piston working therein andhaving an admission port, a main exhaust passage, a main exhaust port, amain valve adapted to control said admission and exhaust normally, andmeans for actuating and governing said main valve; said valve gear beingfurther characterized by an auxiliary exhaust passage and an auxiliaryvalve for controlling said last-named passage, means to co-ordinate theoperation of said main and auxiliary valves whereby free exhaust fromsaid cylinder may be permitted through said auxiliary passage free fromcontrol by said main valve, and means to control said auxiliary valveindependently of said main valve.

9, A valve gear characterized by the elements combined and co-operatingas set forth in claim 8, and further characterized by having saidauxiliary-valve-control means formed with a secondary link and adjustingmeans therefor.

10. A valve gear characterized by the elements combined and co-operatingas set forth in claim 8, and further characterized by having saidauxiliary-valve-control means provided with a secondary link, andadjusting means comprising a system of manually operable levers and apivot block connected to said auxiliary valve and working in saidsecondary link.

11. A valve gear characterized by a main valve link, connected to theworking parts of an expansion engine for controlling admission andexhaust of the fluid pressure medium, and also characterized by anauxiliary valve having a secondary link connection with said rst-namedlink,

whereby said secondary link and auxiliary valve are co-ordinated with,and actuated by, said rstnamed link, each of said links being providedwith means for adjustment of one link motion independently of the other.

12. valve gear characterized by a main valve link, connected to theWorking parts of an expansion engine for controlling admission andexhaust of the fluid pressure medium, and also characterized by anauxiliary valve having a secondary link connection with said first-namedlink, whereby said secondary link and auxiliary valve are coordinatedwith, and actuated by, said firstnamed link, each of said links beingprovided with means for a reversal of one link motion independently ofthe other.

13. A valve gear characterized by a main valve link, connected to theWorking parts of an expansion engine for controlling admission andexhaust of the uid pressure medium, and also characterized by anauxiliary valve having a secondary link connection with said first-namedlink, whereby said secondary link and auxiliary valve are coordinatedwith, and actuated by, said rst-named link, each of said links beingprovided with an arm, said arms being extended in the same direction andbeing connected pivotally with a common rod which serves to connect andco-ordinate the movements of said links while permitting independentadjustment of each; said gear being also characterized by means foreiecting manually and selectively said adjustments.

14. A valve gear for an expansion engine of the type characterized by aHuid-pressure cylinder with a reciprocating piston working therein andhaving main admission and exhaust ports and a main Valve adapted tocontrol said ports for general admission and exhaust purposes; saidvalve gear being further characterized by an auxiliary exhaust passageand an auxiliary valve therefor, with means to control said auxiliaryvalve selectively to provide free exhaust in any cut-off position of themain valve.

JOHN MERRITT CLARK.

